The present invention relates to balloons for medical catheter applications, wherein a catheter with a balloon at the proximal end is positioned within a bodily conduit and inflated to expand the conduit, and to methods of fabrication of such balloons.
Typical balloon catheters have a balloon fastened around the exterior of a hollow catheter tube or shaft, with the balloon in fluid flow relation with the interior of the shaft. The shaft provides a fluid supply for inflating the balloon.
Examples of such balloon catheters are catheters for prostate therapy, TTS endoscopic catheters for gastrointestinal use, and PTA and PTCA catheters for angioplasty. For example, coronary angioplasty can involve the insertion of a PTCA (percutaneous transluminal coronary angioplasty) catheter through a patient's artery to an arterial stenosis, and injecting a suitable fluid into the balloon to inflate it. The inflation expands the stenosis radially outwardly and compresses it against the artery wall to increase the cross-sectional area of the artery so that the artery has an acceptable blood flow rate.
Some known catheter balloons are fabricated from non-compliant materials such as polyethylene terephthalate (PET) or Nylon. Non-compliant balloons present the advantages of high burst strength and predetermined maximum diameter. These balloons can prevent damage to tissues due to over-inflation, since they do not increase in diameter significantly beyond the point of full inflation. Their disadvantages, however, include stiffness and poor foldability. Further, on deflation these balloons can present sharp edges and corners which can cause trauma to bodily tissues as the catheters are withdrawn.
Other known balloons are fabricated from compliant materials such as polyethylene (PE) or ethylene vinyl acetate (EVA). The diameter of these balloons is dependent on the pressure of the inflation fluid. The compliant balloons are easily folded, and are softer than the non-compliant balloon, thus are less likely to cause trauma during their passage through the body. However, the variable diameter of the non-compliant balloons must be carefully monitored to prevent tissue damage and catastrophic failure of the balloon during inflation. They can also present the disadvantages of lower tensile strength than the non-compliant balloons. Increasing the wall thickness to offset the lower tensile strength can present an undesirably large profile in the folded balloon.
It would be desirable to have a medical catheter balloon which combines the best properties of the compliant and non-compliant balloons, with low compliance, high burst strength, low folded profile, softness, and pliability. The invention described herein was developed to address that need.